As an inputting operation unit for various electronic apparatus, input devices provided with push-button type input means are in wide use such as in portable telephones. By manipulating such an input device, telephone numbers can be inputted into a portable telephone.
Also, as Internet connectivity environment is put in place in recent years, frequent Internet access is practiced giving rise to need to freely move a cursor on a display.
In order to make such an operation, input devices that combine a position input device for moving a cursor on a display and a push-down device for inputting telephone numbers and the like have been contrived.
A description of such a conventional input device will be given below with reference to FIG. 9.
FIG. 9 is a sectional view of a conventional input device.
The position inputting operation using this conventional input device is an action of tracing the top of key 101 or the surface of keymat 102 with a finger. Touch pad 104 is disposed under keymat 102. As a finger has electrical conductivity, the electrostatic capacitance of an electrode (not shown) inside touch pad 104 changes by a tracing action. Position coordinate is detected by inputting the information on the electrostatic capacitance change into a controller (not shown) for processing in a predetermined way by the controller.
Also, for push-down inputting operation, a push-down switch, for example, is used. An indication marking (not shown) is provided on the primary surface on the top face of key 101. Dome-shaped element 107 made of an elastic thin metal sheet having a circular or elliptical contour and a convex top portion is disposed on substrate 106 at a location corresponding to the position of the indication marking. A push-down type switch is thus constructed in which dome-shaped element 107 functions as a movable contact. Downwardly protruding columnar section 103 integrally formed with key 101 passes through opening 105 provided on touch pad 104 in order that the center of dome-shaped element 107 can be pushed by the bottom edge of columnar section 103. When key 101 is pushed down, dome-shaped element 107 is deformed by being pushed by columnar section 103, and its bottom face makes at least two conductive elements 108 that are correspondingly disposed on substrate 106 conducting with each other thus detecting an input.
As a conventional art literature relating to the present invention, Japanese Translation of PCT Publication 2004-535712, for example, is known.
In such a conventional input device like this, it is easy to configure a device by combining keymat 102 and touch pad 104. However, in the step of combining each key 101 of keymat 102 attached with touch pad 104 and each dome-shaped element 107, if there is a clearance between columnar section 103 and dome-shaped element 107, when depressing key 101 a difference is caused between the stroke of columnar section 103 coming into contact with dome-shaped element 107 and the stroke of columnar section 103 depressing and deforming dome-shaped element 107 while, at the same time, producing a reaction force from dome-shaped element 107. The difference in the strokes is felt by the finger making the touch uncomfortable feeling. For this reason, it is necessary to adjust the height so that the tip of columnar section 103 precisely comes in contact with dome-shaped element 107. This causes an increase in the manufacturing cost as the workability of adjustment in the manufacturing process is poor.
On the other hand, by directly or indirectly joining each of columnar section 103 of keymat 102 which is attached to touch pad 104 to corresponding dome-shaped element 107, the clearance between columnar section 103 and dome-shaped element 107 can be eliminated and worsening of touch of push-down operation can be suppressed. However, when columnar section 103 is joined at a position displaced from the center of dome-shaped element 107, the state of inversion of dome-shaped element 107 during push-down operation becomes asymmetrical and original reaction force and stroke cannot be obtained thus worsening the touch feeling. For this reason, it is necessary to join them while strictly controlling the dimension of keymat 102 which is normally formed into a shape having a plurality of columnar sections 103 made of an elastic material such as silicone rubber, and positioning each columnar section 103 to the center of respective dome-shaped elements 107. Accordingly, even when adopting this configuration, workability further worsens thus suffering an increase in the cost.